View Full Version : L100 Crossover & capacitors & nasty noises

01-30-2005, 05:07 PM
Had a nasty noise from my old L100s last night - sounded like a capacitor dischaging...at least I hope that is what it was, otherwise it could be something expensive happening inside there or in my amp.:blink:
I have parts coming to replace pots with L_Pads per Giskard's posting to the Project May thread - plus 0.01 mf capacitors also per Giskard's pos t, but don't want to pull things apart until those bits arrive. So - does anyone know the mf value of the original capacitors in the L100 crossover? That way I can have them on hand when the other bits arrive, and save myself some time...

01-30-2005, 05:13 PM
Oops - sorry Don, I should have checked to see who did the work on those crossovers. Humble apologies....:banghead:

02-02-2005, 03:26 AM
The midrange uses a series 8.0uf and the tweeter uses a series 3.0uf. These are the values shown for crossover N3112C.
John Lovda

02-02-2005, 02:51 PM
Thanks for your help - I couldn't find that info anywhere, although rummaging around the i'net I did find a table that showed generic values. Is N311C JBL's disignation for the L100 crossover? By the time I'm finished I suspect the only original bits in them will be the masonite board and some wire...oh well
Geoff S.

02-02-2005, 08:19 PM
All the L100A crossovers I've seen have been labelled "N100" or "N100A". The N3112, AFAIK, is the same thing electrically, but a different physical layout...


02-02-2005, 08:48 PM
Thanks Gordon. Certainly the only labelling I can see on Don C's posting (in the Project May thread #44) is as you say - L100. Can't even see the value of the caps, probably because it is tucked away underneath, or not on them at all? I guess I'll find out when I actually get at the little beasts in a week or so's time.

Don C
02-02-2005, 09:44 PM
I know that these have been posted before, but WTH, here they are again:

02-06-2005, 06:42 PM
Yo!!! Now that's what I've been looking for - the diagrams even look like they are for the crossovers in your Project May postings... Sorry for the delay in responding - I've been away on a "somewhat lost" 3-day weekend with a bunch of mad Poles - guess you will know what I mean.

Now all I have to do is wait for the parts to turn up...

Thanks heaps, Don. Not sure where those original postings that you mention are, but this one is certainly very very useful - even confirms what I thought I was going to find inside those nice wood-veneer boxes - all I've got to do now if not mess up those foil caps. (Actually I think they are loosing their grip on things anyway - I can get a finger-nail under the edge - so with a little bit of heat, and a spatula of some kind, the job might not be so bad!!

Geoff S

07-22-2005, 08:35 AM
I am upgrading and restoring a pair of L-88 Plus speakers by adding LE5-5 midrange drivers and building completely new crossover networks with better capacitors and new L-Pads. The schmatic I chose to use is the N3112C but I noticed something strange. Crossover N100 looks exactly the same as the N3112C but the driver phasing is different:
N3112C: Low=(-), Mid=(+) and High=(-)
N100: Low=(+), Mid=(+) and High=(-)
N36: Low=(+), Mid=(+) and High=(+)

I suppose I could fiddle with them and experiment with various phasings but I really want to just put everything together once and be done. Besides, the L25 and L5-5 drivers have polarized connectors so flipping the phase requires resoldering wires on the crossover.

Any experienced builder know the optimal phasing arrangement? http://audioheritage.org/vbulletin/images/smilies/banghead.gif

john Lovda

07-22-2005, 08:58 AM

I'm at a complete loss at this point as to how to get this information across.
I've posted all this stuff over and over and over and over. :blah: :blah: :blah:

Anyone have any ideas?

I guess I really need to get to work on the Technical Documentation Project.....

What kind of disk space are we sucking up on the storage devices?


07-22-2005, 11:52 AM
Thank you.

The two networks are identical regarding phasing but there is a strange twist. On every other network I have seen, pin 3 of the L-pad is always the input, pin 2 connects to the positive connector on the driver and pin 3 connects to ground and the low side of the driver. On the N88, pins 1 and 3 seemed to be flipped.

John Lovda